Skin cancer is cancer that starts as a growth of cells on the skin. The cells can invade and destroy healthy body tissue. Sometimes the cells break away and spread to other parts of the body.

Many kinds of skin cancer exist. The most common skin cancers are basal cell carcinoma and squamous cell carcinoma. While these are the most common, they often can be cured. The most dangerous form of skin cancer is melanoma. It is more likely to spread, making it harder to cure.

Most skin cancers happen on skin that gets a lot of sunlight. The light that comes from the sun is thought to cause most skin cancers. You can reduce your risk of skin cancer by covering your skin with clothes or sunscreen to protect it from the sun.

Some skin cancers happen on skin that doesn't typically get sun. This likely means that something else is causing these cancers. To reduce your risk of these kinds of skin cancers, check your skin regularly for any changes. Report these changes to your healthcare professional.

Symptoms

What skin cancer looks like

Signs and symptoms of skin cancer include:

• A new growth on the skin that might look like a mole, a bump or a scab.
• A rough patch on the skin.
• A sore on the skin that won't heal.
• Changes to a mole or freckle, such as getting bigger or changing color.
• Itchy skin around a skin growth.
• Pain around a skin growth.

Where skin cancer happens

Most skin cancers happen on parts of the body that get a lot of sun. This includes the scalp, face, lips and ears. Other parts of the body that might get sun include the arms, backs of the hands, back and legs.

Skin cancer also can happen on skin that typically doesn't get sun. This includes the palms of the hands, the genitals, and under the fingernails and toenails. When skin cancer happens in people with Black or brown skin, it tends to happen in these places that don't typically get sun.

When to see a doctor

Make an appointment with a doctor or other healthcare professional if you notice any changes to your skin that worry you.

Causes

Most skin cancers are caused by exposure to light from the sun. The light that comes from the sun is a kind of ultraviolet light. That kind of light also can come from tanning beds and tanning lamps. Ultraviolet light contains radiation that changes the DNA inside skin cells and leads to skin cancer.

Not all skin cancers happen on skin that typically gets a lot of sun. This means something else also causes skin cancer. It's not always clear what causes skin cancer. But healthcare professionals have found some things that increase the risk. These include having a weakened immune system and having a family history of skin cancer.

Skin cancer starts when skin cells develop changes in their DNA. A cell's DNA holds the instructions that tell the cell what to do. In healthy cells, the DNA tells the cells to grow and multiply at a set rate. The DNA also tells the cells to die at a set time.

In cancer cells, the DNA changes give different instructions. The changes tell the cancer cells to grow and multiply quickly. Cancer cells can keep living when healthy cells would die. This causes too many cells.

The cancer cells can invade and destroy healthy body tissue. In time, cancer cells can break away and spread to other parts of the body. When cancer spreads, it's called metastatic cancer.

Risk factors

Factors that may increase the risk of skin cancer include:

• Skin that sunburns easily. Anyone of any skin color can get skin cancer. But the risk is higher in people with skin that sunburns easily. The risk of skin cancer also is higher in people who have blond or red hair, light-colored eyes or freckles.
• Light from the sun. Ultraviolet light from the sun increases the risk of skin cancer. Covering the skin with clothes or sunblock can help lower the risk.
• Light from tanning beds. People who use indoor tanning beds have an increased risk of skin cancer. The lights used in tanning beds give off harmful ultraviolet light.
• A history of sunburns. Having had one or more sunburns that raised blisters increases the risk of developing skin cancer. If the sunburns happened during childhood, they increase the risk of getting skin cancer as an adult even more.
• A history of skin cancer. People who've had skin cancer once are much more likely to get it again.
• A family history of skin cancer. If a blood relative, such as a parent or sibling, had skin cancer, you may be more likely to get skin cancer.
• A weakened immune system. If the body's germ-fighting immune system is weakened by medicine or disease, there might be a higher risk of skin cancer. People with weakened immune systems include those taking medicine to control the immune system, such as after an organ transplant. Some health conditions, such as HIV infection, also can weaken the immune system.

Prevention

Most skin cancers can be prevented by protecting yourself from the sun. To lower the risk of skin cancer you can:

• Stay out of the sun during the middle of the day. For much of North America, the sun's rays are strongest between about 10 a.m. and 3 p.m. Plan outdoor activities at other times of the day. When outside, stay in shade as much as possible.
• Wear sunscreen year-round. Use a broad-spectrum sunscreen with an SPF of at least 30, even on cloudy days. Apply sunscreen generously. Apply again every two hours, or more often if you're swimming or sweating.
• Wear protective clothing. Wear dark, tightly woven clothes that cover your arms and legs. Wear a wide-brimmed hat that shades your face and ears. Don't forget sunglasses.
• Don't use tanning beds. The lights in tanning beds give off ultraviolet light. Using tanning beds increases the risk of skin cancer.

• Check your skin often and report changes to your healthcare team. Look at your skin often for new growths. Look for changes in moles, freckles, bumps and birthmarks. Use mirrors to check your face, neck, ears and scalp.

  Look at your chest and trunk and the tops and undersides of your arms and hands. Look at the front and back of your legs and your feet. Look at the bottom of the feet and the spaces between your toes. Also check your genital area and between your buttocks.

Diagnosis

A skin cancer diagnosis often starts with an exam of your skin. A healthcare professional might remove some skin to test it for cancer.

Skin cancer exam

A healthcare professional might start by asking about your symptoms and looking at your skin.

Skin cancer biopsy

A biopsy is a procedure to remove a sample of tissue for testing in a lab. To get a piece of skin, a healthcare professional may use a cutting tool to cut away some or all of the worrying skin growth. Often a skin biopsy happens in a healthcare professional's office. Medicine numbs the area so you won't feel pain.

The skin tissue sample goes to a lab for testing. Tests can show whether the sample contains cancer cells.

Skin cancer staging tests

Some people with skin cancer may need other tests to find out whether the cancer has spread. This is called cancer staging. The stage of the cancer tells the healthcare team about its size and whether it has spread.

Not everyone with skin cancer needs cancer staging. Most skin cancers don't spread. For example, basal cell carcinoma and squamous cell carcinoma aren't likely to spread. These are the most common types of skin cancer. If your healthcare professional thinks there's a risk that your cancer may have spread, you might have staging tests. The cancer is more likely to spread if it grows large or if it's a kind of skin cancer that often spreads, such as melanoma.

Skin cancer staging tests might include:

• Imaging tests. Imaging tests make pictures of the inside of the body. The pictures might show the size of the skin cancer and whether it has spread. Imaging tests might include computerized tomography scans, also called CT scans, and magnetic resonance imaging scans, also called MRI scans.
• Sentinel lymph node biopsy. A sentinel lymph node biopsy is a procedure to remove some lymph nodes for testing. When skin cancer spreads, it typically goes to the lymph nodes first. The sentinel nodes are the ones where the skin cancer is most likely to spread first. If these nodes don't have any signs of cancer, it's likely that the cancer hasn't spread.

Skin cancer stages

Your healthcare team uses the results of these tests to give your cancer a stage. The stages of skin cancer range from 0 to 4. Exactly what these numbers mean depends on the kind of skin cancer and where it happens on the body. In general, the lower numbers mean the skin cancer is small and only affects the outer layer of the skin. As the skin cancer grows deeper into the skin or spreads, the stages get higher. A stage 4 skin cancer often is a cancer that has spread to the lymph nodes or to other parts of the body.

Treatment

Treatment for skin cancer can involve surgery to remove the cancer or treatments applied to the skin to kill the cancer cells. Sometimes stronger cancer treatments are needed for skin cancer. These might include radiation therapy, chemotherapy, targeted therapy and immunotherapy.

Skin cancer treatments can include:

• Skin creams. Some medicines for skin cancer come as skin creams that you apply to the area of cancer.
• Curettage and electrodessication. This treatment involves removing the top of the skin cancer with a scraping tool called a curet. Then an electric needle is used to sear the base of the cancer.
• Photodynamic therapy. Photodynamic therapy is a two-stage treatment that combines light energy with a medicine called a photosensitizer. The photosensitizer kills the cancer cells when activated by light.
• Surgery. Skin cancer surgery often involves removing the cancer and some of the healthy tissue around it.
• Mohs surgery. Mohs surgery involves removing the skin cancer layer by layer. Each time a layer is removed, the surgeon uses a microscope to look for cancer cells. The surgery continues until no cancer cells are left. This kind of surgery lets the surgeon take out the cancer without removing too much of the healthy skin around it.
• Radiation therapy. Radiation therapy treats cancer with powerful energy beams.
• Chemotherapy. Chemotherapy treats cancer with strong medicines.
• Targeted therapy. Targeted therapy for cancer is a treatment that uses medicines that attack specific chemicals in the cancer cells. By blocking these chemicals, targeted treatments can cause cancer cells to die.
• Immunotherapy. Immunotherapy for cancer is a treatment with medicine that helps the body's immune system kill cancer cells. The immune system fights off diseases by attacking germs and other cells that shouldn't be in the body. Cancer cells survive by hiding from the immune system. Immunotherapy helps the immune system cells find and kill the cancer cells.

Preparing for an appointment

Make an appointment with a doctor or other healthcare professional if you have any skin changes that worry you. If your healthcare professional thinks you might have skin cancer, that person may refer you to a specialist. Often this is a doctor who diagnoses and treats skin conditions, called a dermatologist.

Appointments can be brief, so it's a good idea to be prepared. Here's some information to help you get ready.

What you can do

Ask a family member or friend to go with you to the appointment to help you remember the information you get.

Make a list of:

• Your medical history, including other conditions for which you've been treated.
• All the medicines, vitamins and natural remedies you take, including doses.
• Questions to ask your healthcare team.

Some basic questions to ask about skin cancer include:

• Do I have skin cancer?
• What type of skin cancer do I have?
• Will I need other tests?
• How quickly does my type of skin cancer grow and spread?
• What are my treatment options?
• What are the potential risks of each treatment?
• Will surgery leave a scar?
• Do I have an increased risk of getting more skin cancers?
• How can I reduce my risk of more skin cancers?
• Should I have regular skin exams to check for skin cancer?
• Should I see a specialist? What will that cost, and will my insurance cover it?
• Is there a generic alternative to the medicine you're prescribing for me?
• Are there brochures or other printed material that I can take with me? What websites do you recommend?
• What will determine whether I should plan for a follow-up visit?

Ask any other questions that you think of during your appointment.

What to expect from your doctor

Your healthcare professional likely will ask about your symptoms. Be ready to answer questions such as:

• When did you first notice your skin changes?
• Have you noticed a skin lesion that has grown or changed?
• Do you have a skin lesion that bleeds or itches?
• How bad are your symptoms?